MONTAUK, N.Y. — At the eastern end of Long Island, on the South Fork, tucked among the wobbly clam shacks and the steroidal homes, there are a few small grassy plots sectioned off by short chicken-wire fences. The wire is rusty, and the wooden posts that hold it upright are weathered to a milky gray. One plot is not far from a cliff that drops straight to the sea. Another is within eyeshot of a condominium association’s swimming pool.

There are no signs or other indications of purpose or origin, but each quietly safeguards a botanical gem: the delicate wildflower known as sandplain gerardia, New York’s only federally listed endangered plant species.

There are only 12 known populations of sandplain gerardia (Agalinis acuta) in the country, and six of them grow on Long Island — but nowhere else in the state. This year, with punishing drought conditions leaving great swaths of the country, including the South Fork, pleading for a drink, botanists are fearing the worst for the plant. (Spring rainfall on Long Island was 8 to 12 inches below normal.) Even if you know where the plots are, sandplain gerardia is harder than ever to find.

Everything about the plant speaks of fragility. Its bubble-gum pink flowers are no wider than a penny, and when they arrive — the plant blooms in late summer — they stay for just a day. The plant is only about 10 inches tall, with branches as thin as floss. Sandplain gerardia quickly gets lost among Long Island’s heartier coastal grasses — all that Indian grass and big blue stem waving from along Montauk Highway.

The Montauk plots are owned by various state and local agencies, but the Long Island branch of the Nature Conservancy has agreed to monitor them. Once a year, Paul D’Andrea, a former chef and self-taught botanist who joined the environmental group eight years ago, visits the sites and counts the plants. He sends the data to the federal Fish and Wildlife Service, where officials decide whether the plots should be expanded or somehow fortified (though officials rarely choose to plant new seeds for fear of contaminating the native species).

Photo

Paul D’Andrea searched one of Long Island’s six unmarked plots last week for sandplain gerardia.Credit
Michael Peed/The New York Times

“We’ve had years in the past with fields full of pink, years when you just say, ‘Wow,’ ” Mr. D’Andrea said on a recent weekday, as he prepared to begin his count. “But because of the summer’s drought, I can almost guarantee that this will not be a wow year.”

The historical arc of sandplain gerardia is a common one: hundreds of millions covered Long Island before the usual suspects — roads, beach houses, strip malls — took over. One cluster, along the Long Island Rail Road tracks, was wiped out when a worker sprayed it with weed killer.

In the early 1980s, Rolf Martin, a graduate student in chemistry at Brooklyn College, fearing the plant extinct, offered $100 to anyone who spotted a wild specimen. No one did. But by 1988, when the plant was placed on the endangered species list, the highest protection an American botanical specimen can receive, 814 plants had been discovered.

Today, there are stable sandplain gerardia populations on the Sayville Grasslands and the Hempstead Plains. The four populations on Montauk, fenced off but otherwise unpublicized for fear of sabotage, are the smallest and the most precarious.

Mr. D’Andrea wore a cotton jumpsuit that buttoned down the middle, like a house painter or a ghostbuster. He had tucked the bottoms into his rubber mud boots, and, using duct tape, sealed the gap between. “Ticks,” he said. “Tiny nymphs. They’ll gather on you like smudges of coffee grinds.”

Photo

The wildflower is the only federally listed endangered plant species in New York State.Credit
Department of Environmental Conservation

Carrying a clipboard, he swung his legs over the first fence. The plot was 30 feet by 10 feet. No pink was apparent. He scoured the ground, using a pencil to push larger plants aside. “I think that’s one of our friends,” Mr. D’Andrea said, but he was talking about a tick. He brushed off the black speck. Pacing the plot twice more, he finally announced: “I got four plants. One, two, three, four. Not so good.”

At the next plot, Mr. D’Andrea’s tally was higher, at 67. “But last year I think we had 400,” he said. “In the conservation world, large mammals get all the press. But why is this any less important than a polar bear or a monarch butterfly? We don’t know what other species depend on this little flower. We’ve got to protect it.”

After surveying the remaining plots, the number of check marks on Mr. D’Andrea’s clipboard totaled 115. Last year, the count was 1,341. He had spent the afternoon uttering phrases like “Oh, bummer” and “I’m not feeling the love here.”

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“That’s the biggest swing I’ve seen since I’ve been doing this,” said Mr. D’Andrea, yanking the duct tape off his jumpsuit. “To think that millions of sandplain gerardia were once on Long Island. I’ll pass this data on, but there’s not a whole lot to do.

“We’ll just have to hope that the seeds are down there, hanging on until next year. If it’s a wetter year, maybe we’ll get lucky.”

Just then, a monarch butterfly flew by, and was spotted without effort.

A version of this article appears in print on September 6, 2012, on Page A24 of the New York edition with the headline: Despite Protections, Botanists Fear Drought’s Toll on a Pink-Petaled Rarity. Order Reprints|Today's Paper|Subscribe